Derivations of upper limits on Saturn’s trace gases in the well-mixed case. For all thirteen gases, the left panel shows the line to continuum ratio in the data (circles) compared to a number of models (grey solid lines), and the right panel shows the degradation of the χ² parameter as we increase the mole fraction. Dashed lines show the 1σ and 3σ confidence limits. For some species we show only the line which provided the best constraints on the upper limit.